Vehicles are being designed to include high strength, low elongation materials such as carbon fiber reinforced polymers, polypropylene, magnesium, ceramics, and the like. For example, grille opening reinforcements made of carbon fiber reinforced polymers are strong and lightweight but are brittle and tend to shatter or disintegrate in a high energy collision.
Safety restraint performance depends upon peripheral sensors such as front crash sensors. Crash discrimination capabilities of front crash sensors depend, in part, upon the physical properties of the mounting structure and the location of the front crash sensors. The mounting structure should be ductile, deformable, strong and elastic so that the front crash sensors follow overall vehicle deceleration profiles during high energy impacts.
The grille opening reinforcement is located in a vehicle close to the front end but recessed behind the bumper. Locating the front crash sensors in this location enhances control of safety restraints that are controlled by a restraints control module located inside the passenger compartment. Spacing the front crash sensors relative to other crash sensors facilitates analysis of the sensor signals and distinguishing different types of collision scenarios. Providing two front crash sensors symmetrically on the vehicle facilitates distinguishing, for example, a full frontal collision from an offset collision, or a side impact collision.
Front crash sensors cannot be effectively attached to a brittle grille opening reinforcement because the sensors may become free-floating when the grille opening reinforcement disintegrates. Free-floating front crash sensors with single axis accelerometer sensors are unable to provide useful crash data to the restraints control module and may become electrically disconnected from the restraints control module.
In one approach, a bracket, commonly referred to as a “boomerang bracket,” is attached in front of the grille opening reinforcement and attached to the frame rails in the front end of the vehicle. With this approach, the front crash sensors were located in a less than optimal location that is too low for low riding vehicles colliding with higher ground clearance vehicle. The boomerang bracket approach also increases the complexity of the front end assembly process, increases weight and may reduce sensor effectiveness.
In another approach, five steel parts are joined by a composite material overlay and connected to the frame rails and the “shotgun” (fender wall support). Problems with this type of structure are that the part is complex and is difficult to install on the vehicle. These problems increase part cost, labor costs and add weight to the vehicle.
The above problems and other problems are addressed by this disclosure as summarized below.